1. Field
Benzoylthiourea or benzoylthiourethane derivatives as cure accelerators in primers for two step adhesive systems are provided.
2. Brief Description of Related Technology
Curable adhesive and sealant compositions oftentimes rely on curatives to make them commercially attractive options for end users. Curable adhesive and sealant compositions come in one part formats, two part formats and two step formats depending on the performance profile they are designed to meet and the constituents used to prepare the compositions. Anaerobic adhesives are prominent one part compositions and generally are well-known. See e.g., R. D. Rich, “Anaerobic Adhesives” in Handbook of Adhesive Technology, 29, 467-79, A. Pizzi and K. L. Mittal, eds., Marcel Dekker, Inc., New York (1994), and references cited therein. Their uses are legion and new applications continue to be developed.
Conventional anaerobic adhesives ordinarily include a free-radically polymerizable acrylate ester monomer, together with a peroxy initiator and an inhibitor component. Oftentimes, such anaerobic adhesive compositions also contain accelerator components to increase the speed with which the composition cures.
Anaerobic cure-inducing compositions ordinarily used in commercial anaerobic adhesive and sealant compositions to induce and accelerate cure ordinarily include saccharin, toluidines, such as N,N-diethyl-p-toluidine (“DE-p-T”) and N,N-dimethyl-o-toluidine (“DM-o-T”), acetyl phenylhydrazine (“APH”), maleic acid, and quinones, such as napthaquinone and anthraquinone. See e.g. U.S. Pat. No. 3,218,305 (Krieble), U.S. Pat. No. 4,180,640 (Melody), U.S. Pat. No. 4,287,330 (Rich) and U.S. Pat. No. 4,321,349 (Rich).
GC Corporation submitted to the U.S. Patent and Trademark Office a patent application, which published as U.S. Patent Application Publication No. 2010/0249266, and is directed to a polymerizable composition comprising a first paste and a second paste, where the first paste comprises a polymer of α,β unsaturated monocarboxylic acid or α,β unsaturated dicarboxylic acid, water, and a hydroperoxide as a peroxide, and where the second paste comprises a (meth)acrylate compound not having an acid group, fluoroaluminosilicate glass powder, a thiourea derivative as a reducing material, and a vanadium compound as a polymerization accelerator.
Notwithstanding the state of the technology, there is an on-going desire to find alternative technologies for accelerating the cure of curable compositions to differentiate existing products and provide supply assurances in the event of shortages or cessation of supply of raw materials. Accordingly, it would be desirable to identify new materials, which function as accelerators for curable compositions.